1. Field of the Invention
This invention relates to an optical recording apparatus, an optical recording method for an optical recording medium, and an optical recording medium.
2. Description of the Related Art
In recent years, it has been popularized to digitally record a content of audio data, video data or like data on an optical recording medium such as a DVD-ROM (Digital Versatile Disc Read Only Memory) and distribute the optical recording medium. Thus, an optical recording medium reproduction apparatus having a function of reproducing information recorded on such an optical recording medium as mentioned above such as a DVD reproduction apparatus is provided as a consumer appliance for exclusive use. Further, that, if DeCSS software and software for copying are installed into a DVD reproduction apparatus incorporated in an ordinary PC and the DVD reproduction apparatus is controlled by a CPU (Central Processing Unit) to cancel the CSS applied to a DVD-ROM to place the DVD-ROM into a DVD-ROM of plaintext, whose digital data (sector data) can be copied as it is for each sector on a digital recording medium such as an optical recording medium, a tape or a hard disk. A copy of sector data from such a DVD-ROM or such a DVD recording medium as hereinafter described as it is hereinafter referred to as DVD copy.
Meanwhile, an optical recording medium for implementing the object of storage and distribution of contents or software is provided not only in the form of an optical recording medium for reproduction only like a DVD-ROM described hereinabove but also in other various forms like write-once ready many or rewritable optical recording media. For example, an optical recording medium is provided in the form of a DVD-R, a DVD-RW or a DVD-RAM which are optical recording media standardized by the DVD Forum which is an international organization which conducts publicity activities for establishment of standards for and popularization of the DVD. Or, an optical recording medium is provided in the form of a DVD+R or a DVD+RW which are standardized by the DVD+RW Alliance which promotes development and popularization of a rewritable DVD format which has wide compatibility. Such DVDs as mentioned above are hereafter referred to collectively as DVD recording media. Such DVD recording media are preformatted such that information of a content, software or the like (such information is hereinafter referred to as post pre-format recording information) is recorded on the DVD recording media utilizing the pre-format information. Further, DVD recording apparatus as optical recording apparatus for recording information on such DVD recording media and DVD recording and reproduction apparatus as optical medium recording and reproduction apparatus having both of recording and reproduction functions are popularized as storage devices for consumer appliances and PCs in recent years. Using such apparatus, a general user can duplicate digital information readily.
Since post pre-format recording information recorded on such a DVD recording medium as described above can be read by a DVD reproduction apparatus or a DVD recording and reproduction apparatus, as popularization of the DVD recording and reproduction apparatus proceeds, such various DVD recording media as mentioned above have come to be generally used for the distribution of a comparatively small number of distribution destinations although they are not distributed to such a great number of distribution destinations as that of DVD-ROMs.
Thus, a problem has occurred in regard to how to prevent DVD copying similarly to DVD-ROMs. However, an effective countermeasure for preventing DVD copying different from the countermeasure described above for prevention of duplication of DVD-ROMs has been proposed from a point of view unique to DVD recording medium. The effective countermeasure mentioned is disclosed, for example, in the pamphlet of International Publication No. WO 2005/050638 (hereinafter referred to as Patent Document 1).
In Patent Document 1, it is proposed to record a signal on a DVD recording medium intentionally changing the signal format of the signal from that provided by the standards (DVD standards) prescribed in order to assure the compatibility as described in (1) to (6) below to make it difficult to use a PC to read out the signal from the DVD recording medium thereby to compulsorily stop DVD copying: (1) coding in a rule other than EFM+ (Eight to Fourteen Modulation plus); (2) alteration of the format of the ECC (Error Correction Code); (3) alteration of the format of the ID (Identification Data); (4) alteration of the IED (ID Error Correction) code; (5) alteration of the format of the CPR_MAI (Copyright Management Information); and (6) alternation of the format of the EDC (Error Detection Code).
The DVD copying prevention function disclosed in Patent Document 1 relies upon the following principle. In particular, in an ordinary reproduction operation wherein a signal is read out from a DVD recording medium, data are accessed nonlinearly to reproduce at least one linked content in an interactive fashion. Upon such an ordinary reproduction operation, even if one of the processes (1) to (6) described above is applied so as to make it difficult to read information of some sectors, the reproduction function can be assured. On the other hand, where information from a DVD recording medium is copied on a DVD, data is accessed linearly. In particular, a DVD reproduction apparatus or a DVD recording and reproduction apparatus provided in a PC in which software for data copying of a DVD recording medium is installed reads data (sector data) for each sector and duplicates the sector data one by one to another medium. Therefore, where a DVD recording medium includes sector data to which any of the processes (1) to (6) described above is applied, the data reproduction function is stopped, and consequently, DVD copying may not be performed.
The DVD copying prevention function based on the principle described above acts effectively in a PC which includes a DVD reproduction apparatus which is used exclusively for data reproduction. However, the DVD copying prevention function does not sometimes act in another PC which includes a DVD recording and reproduction apparatus which has a function of recording information on a DVD recording medium. in order to achieve the object of storage and distribution of software in addition of contents mentioned hereinabove, a DVD reproduction apparatus is provided as a storage device for a personal computer (PC).
The amount of information supplied from such an optical recording medium as described above is as great as, for example, where the optical recording medium is a DVD-ROM, 4.7 GB (gigabytes) in the maximum with one face of the disk. Therefore, if information can be copied readily from an optical recording medium, then the interests of the copyright holder are impaired significantly. From such a point of view, in order to prevent duplication of an output after converted into an analog signal, for example, for a DVD-ROM, a CPS (Content Protection System) and a CGMS (Copy Generation Management System) are used.
Further, taking it into consideration that duplication of information in the form of digital data through use of a PC inflicts a more serious loss on the copyright holder than duplication of information at a stage after conversion into analog data, a countermeasure for prevention of digital duplication is taken in recent years in order to prevent copy of information in the form of digital data. For example, for the DVD-ROM, a CSS (Content Scrambling System) is used. However, the function of the CSS is disabled readily by DeCSS software. In particular, it is the existing situation
In particular, a DVD recording and reproduction apparatus in principle performs a reproduction operation relying upon post pre-format recording information recorded later on a preformatted DVD recording medium. However, a DVD recording and reproduction apparatus has a function of reading, when it may not detect post pre-format recording signal, information from a DVD recording medium (such information is hereinafter referred to as pre-format information) preformatted on the DVD recording medium. Therefore, even if the DVD recording and reproduction apparatus detects some format violation in information of post pre-format recording information to which any of the processes (1) to (6) described hereinabove is applied, for example, information of the ID of the post-format recording information, also it is possible for the DVD recording and reproduction apparatus to read, for example, from wobbles, address information formed as prepits along the wobbles and use the read address information to continue the reproduction. As a result, even if some information may not be read by any of the processes (1) to (6), there is the possibility that the reproduction operation may continue without being stopped thereby to allow data copying to be performed continuously.
It is to be noted that, while the foregoing description is given taking a DVD recording medium as an example, usually this problem occurs similarly also where post pre-format recording information is recorded on an optical recording medium having pre-format information similar to that of a DVD recording medium and the optical recording medium which can be reproduced based on the post pre-format recording information is reproduced using an optical recording and reproduction apparatus to copy sector data as it is.
Meanwhile, Japanese Patent Laid-Open No. Hei 7-235130 (hereinafter referred to as Patent Document 2) discloses a technique relating to logical breakdown by which data which does not appear from a recording system on a recording medium is recorded or physical breakdown of a recording layer. Where a medium on which digital data from a medium having such data as described above is duplicated illegally one by one is used, the logically or physically broken down portion does not generate an error. Therefore, according to the technique of Patent Document 2, a reproduction operation is stopped based on the fact that no such an error as described above occurs.
On the other hand, Japanese Patent No. 3,144,408 (hereinafter referred to as Patent Document 3) discloses another technique relating to duplication prevention of a succeeding program where a preceding program read out precedently exists and then the succeeding program is read out under the environment of execution of the preceding program. In other words, according to the technique of Patent Document 3, a portion which may not be detected by an ordinary computer is provided at part of the succeeding program, and an algorithm for executing the succeeding program bypassing the portion described is provided in the preceding program. Thus, while normal operation with a genuine medium is guaranteed, illegal duplication and execution is prevented.